[GIS] Calculating minimum distance between points and polygons in QGIS

distanceqgisvector

I have two vector layers: one point and one polygon and I want to calculate the minimum distance of each point from the polygons (ie the distance from the closest point of the closest polygon).

Is there any available plugin in QGIS for doing this?

Best Answer

Converting your polygon to points first is a bad idea. You will not be calculating the distance to your polygon, you will be calculating the distance to the closest node of your polygons (not the edges which may be closer). You can use the NNJoin Plugin to get accurate measurements to your polygon. Make sure your layers are in the same projection before doing analysis.

Related Solutions

[GIS] Calculating minimum distance between points using PostGIS

You can use this following queries (these operations use a temporary table):

-- add distance_min and nearest_id columns
alter table tab_Cities add column distance_min float;
alter table tab_Cities add column nearest_idpoint varchar(10);

--create temp table
DROP TABLE IF EXISTS table_temp;
select a1.gid as id_1, a2.gid as id_2, ST_Distance(a1.geom, a2.geom) as distance
INTO table_temp
    from tab_Cities a1 , tab_Cities a2
    where ST_DWithin(a1.geom, a2.geom, 5000)
    -- 5000 is like a buffer of 5000 meters around your point
    -- You can use a suitable radius for your points
    and a1.gid <> a2.gid ;

--update distance_min
update tab_Cities set distance_min = 
(
select distance 
from table_temp 
where tab_Cities.gid = table_temp.id_1 
order by distance limit 1
),
                      nearest_idpoint = 
(
select id_2 
from table_temp 
where tab_Cities.gid = table_temp.id_1 
order by distance limit 1
);
--DROP TABLE temp
DROP TABLE IF EXISTS table_temp;

Best Answer

Related Solutions

[GIS] Calculating minimum distance between points using PostGIS

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